The present invention relates generally to electronic generation of sound, and more specifically to methods and apparatuses that generate sound without generating obviously repetitive identical sound.
Electronic sound generators are often used for personal entertainment, recreation, relaxation and even to promote sleep. Users of such equipment find the sound of rain, falling water, wind, among other natural sounds, to be especially beneficial. The sounds may be used to mask out excessively loud and distracting ambient noise, to soothe the user, and even to help the user fall asleep.
Electronic sound generators usually can create several such sounds, and include a switch permitting user-selection of a particular sound. The generators also provide controls for volume and even to permit the user to modulate the effects of some of the sounds.
Some electronic sound generators output synthesized sounds. The nature or other sounds will first have been tape recorded, and a digitized representation of the recorded sounds are then electronically stored in a synthesizer integrated circuit (xe2x80x9cICxe2x80x9d). The IC is then used in an electronic sound generator to output the user-selected synthesized stored sounds for listening.
Other electronic sound generators do not store sounds, but simulate sounds using white noise. Ideally, a xe2x80x9cwhite noisexe2x80x9d generator outputs a wide spectrum of frequencies, each frequency component being of equal amplitude. Sounds associated with running or rushing water, for example, may be readily simulated using a white noise generator. The amplitude of the white noise is often modulated, or changed, using a ramp signal. When the instantaneous magnitude of the ramp varies, the magnitude of the white noise sound will be varied. A control can permit the user to vary varying the rate at which the ramp changes amplitude to produce interesting sound effects from white noise electronic sound generators.
Whether generated from a single digital synthesizer IC, or from a single white noise source, electronic sound generators present the sound to left and right channel speakers or earphones. This can somewhat improve the sound quality perceived by the user, but nonetheless there is considerable room for improvement. The sounds often sound too xe2x80x9cflatxe2x80x9d, with too little perception of sound depth or quality. U.S. Pat. No. 5,619,179 (April 1997) to Smith and assigned to the assignee herein discloses a sophisticated method for electronically enhancing the perceived spatial separation of electronically generated sound. Applicants refer to and incorporate herein by reference said ""179 patent to Smith, for background material.
One problem associated with many electronic sound generators is the somewhat limited repertoire of sounds that are provided and the all too perceivable sensation that the exact same sounds are simply being repeated over and over and over. A listener who selects xe2x80x9craindropxe2x80x9d sounds from an electronic sound generator repertoire soon becomes bored with the generator because after a few seconds, the listener can almost predict what sequence of raindrops falling will be heard next. The sound patterns simply become too repetitious for listening enjoyment or relaxation.
In some sound generators, variations in the sounds heard may occur too abruptly. Portions of an ocean wave sound, for example, may transition too abruptly from a quiet and calm wave sound to a loud rushing wave sound. The sensation can be a soft-loud-soft-loud repetitive pattern that is annoying to the user. In fact, some sound patterns that are too repetitively abrupt are believed to trigger seizures in epileptics.
In summation, there is a need for an electronic sound generator that can produce sounds whose patterns are not precisely repetitive to where a listener can essentially predict the next sequence in the sound. Such generator should provide a greater variety of perceived sound patterns, including patterns not readily recognizable by a listener as having been heard before.
The present invention provides such an electronic sound generator.
The present invention reproduces sounds electronically using at least one multi-channel sound integrated circuit (IC). Normally, within the IC different sounds are stored for reproduction through one or two audio channels (e.g., loud speakers). The present invention recognizes that the same stored sound is playable through more than one channel at a time, including playing through more than one channel with time delays. Further, different sounds may be played from different channels and then mixed and output through a single audio channel.
In this fashion, a stored digital sound of raindrops may be combined with itself, but with a time delay, to vary the perceived pattern. Further, the raindrop sound may be combined with a segment or xe2x80x9csnippetxe2x80x9d of other sounds, a bird chirping, for example, to vary the pattern from one playing to another.
Other features and advantages of the invention will appear from the following description in which the preferred embodiments have been set forth in detail, in conjunction with the accompanying drawings.